As any professional grower or gardener will tell you, Pythium root rot is a nasty pest that, if left untreated, can cause failure of an entire crop in very short order. Formerly classified as a fungus, scientists have learned much more about the varying “strains” of Pythium and have changed its classification to a pathogen. Regardless of the type of pathogen involved, the mechanism of action for the Pythium genus remains the same. Oftentimes Pythium root rot is referred to as “damping off.”

I.General Background As any professional grower or gardener will tell you, Pythium root rot is a nasty pest that, if left untreated, can cause failure of an entire crop in very short order. Formerly classified as a fungus, scientists have learned much more about the varying “strains” of Pythium and have changed its classification to a pathogen. Regardless of the type of pathogen involved, the mechanism of action for the Pythium genus remains the same. Oftentimes Pythium root rot is referred to as “damping off.”

These pathogens directly attack the root system of the plant, causing normally healthy white roots to change color to brown or gray. This typically happens within just a few days of the initial infection of the system. This is followed by a “sliming off” of the roots. (The general texture of healthy roots is somewhat rigid, with “fishbone” style feeder roots emanating from a centrally located tap root.) Rather than feeling rigid and appearing white, they develop the appearance and feel of mush, oftentimes falling off to be circulated in the system. This presents multiple problems, the most obvious of which leaves a plant attempting to grow with no root system to provide sustenance. This infected root mass that is circulating through the system will in fact contaminate the other plants that reside in that system.

There is no doubt that Pythium is much more devastating in a hydroponic application when compared to a soil application. This is due in large part to the fact that Pythium has adapted very well to live in water. Certain varieties of Pythium will produce what are known as zoospores (small, flagellated spores) that are extremely small, motile spores able to move in water. These spores are able to move from plant to plant via the water in the system, colonizing and infecting along the way. They even have the ability to remain viable for long periods of time in soil and in the nooks and crannies of a hydroponic system.

That is not to say that soil/container gardeners should leave Pythium untreated. Regardless of media, the pathogen will eventually find its way to the root system and begin to wreak havoc. But soil gardeners get a distinct advantage in the fight vs. Pythium. The root system of the plant (along with any mycorrhizal networks present) creates a web-like barrier that can slow down the spread the Pythium. The symbiotic relationship between the mycorrhizal fungi and the roots of the plant not only provide enhanced access to carbohydrates, water, and minerals, but also provide additional benefits such as increased resistance to diseases and drought.

Now there are a few important things to note before we begin talking about treatment and prevention. Being that Pythium has the ability to remain behind in a media, while remaining viable, certain preventative measure simply will not work. Typically, large scale farmers will rotate crops and leave some fields unused for several seasons, a process known as fallowing. The central idea behind this technique is to avoid not only the buildup of pathogens and pests, but also to avoid over depletion of the nutrients in the soil. However, due to the hardiness of Pythium and its ability to feed on any dead organic matter, crop rotation is just not a viable preventative measure for treatment. It’s important to focus on the last part of that statement, “Pythium has a unique ability that allows it to consume dead organic matter.” That includes dead leaves and roots, along with a multitude of other food sources.

II.Causes and Tips on General Preventative TechniquesWe understand that the ultimate cause of root rot or “damping off” is by a pathogen. But pathogens don’t just magically appear in our growing environments, they are brought in. Now that implies that they have a suitable environment with which to grow, feed, and ultimately destroy our crops. Unfortunately for us (the growers) the environment in which Pythium thrives happens to be nearly identical to the one that our plants and crops find most enjoyable too. So how can we make the environment as uninhabitable as possible for Pythium, without harming our plants in the process?

Keeping the system clean is just part of it; we also need to make sure the water is clean too. Water that contains any amount of chlorine (nearly all tap water in the U.S. is treated with it to reduce and prevent diseases) will typically be free of most of the harmful pathogens. Growers that use rainwater, run-off water, or even well-water are at a higher risk for having contaminated water. (Simply due to the fact that we have no idea what environments that water has passed through prior to arriving at its destination.)

The inclusion of an enzyme product in your feeding regimen is also an excellent way to prevent the buildup of dead organic matter. This robs any pathogen of a potentially rich food source, which also helps to keep the water clean. Hygrozyme, when used at maintenance doses of 5mL-10mL does a fantastic job of keeping that organic waste from becoming a home to an annoying pest.

Keeping the media over-saturated or improperly oxygenated can also lead to Pythium problems. Too much water will not allow sufficient oxygen into the media, creating an anaerobic environment. This leads to rotting material, and subsequently an excellent place for Pythium to take hold. The addition of air stones to any hydroponic environment is a must, this keeps the nutrient solution richly oxygenated, further preventing any material from rotting. Since air stones are useless in soil, I prefer to add lots and lots of perlite to my soil mixes, this loosens the soil up and makes it drain and breathe easier. Allowing oxygen to the media is an important step in preventing any possible root zone problems.

Water temperature is another important factor in preventing Pythium. The ideal water temperature in a hydroponic environment is 68-70 degrees F. Just some numbers here to put things in perspective a bit: at 50 degrees F, the amount of dissolved oxygen in water is approximately 11.5 mg/l, at 70 F it’s 9 mg/l, and at 90 F it’s 7.5 mg/l. Remember, this is the maximum amount of oxygen that water can hold at a given temperature, nothing we do (aside from changing the temperature) can change that. It’s worth noting that impurities such as salt or heavy metals will cause the saturation levels to decrease even more. So in a hydroponic environment, with nutrients in the reservoir, the amount of dissolved oxygen could be significantly less. Not only are we hurting our plants by providing insufficient oxygen, but we are also providing a more welcoming home for pathogens.

III.Prevention and TreatmentSo, how do we effectively eliminate Pythium from our gardens, and how do we keep it from coming back? First and foremost, and I cannot stress this enough as it is one of the most overlooked means of prevention, Cleanliness, Cleanliness, Cleanliness. I have compiled a list of the Top 10 ways to maintain a clean grown environment, and they’re in no particular order.1. Remove dead matter (including leaves) from the plants, floors, walls, and wherever else they may get stuck. Be sure to move the dead, soiled material to a trash basin that is located outside the grow space. A better method is to destroy the dead matter all together, thereby eliminating the chance of re-infection by dead matter.2.Do not move plants from soil into a hydroponic system. Inevitably some of the soil will remain attached to the root systems, and will provide a nice organic food source for any lingering pathogens.3.Change into clean clothes prior to entering the grow area. There is a plethora of little pests that would like nothing better than to hitch a ride on your clothes or shoes into a nice comfortable grow environment.4.Clean and sterilize all system components between crops. This includes all net pots, buckets, feed and drain lines, pumps, trays, reservoirs, lids, basically anything used to house the plants or the water that feeds them. Don’t forget to also clean the walls, floor, and ceiling just to eliminate any possibilities.5.Keep your nutrient tanks clean!! This should be a given, but I’ve seen and I know many people that only clean the tanks between crops. Personally I rinse and clean my reservoirs every two weeks, and I change the nutrient solution every week. Organic nutrient users will have a large amount of organic matter on the bottom of their tanks, while chemical nutrient users will typically have a salt buildup.6.Avoid at all costs allowing plant material to fall into the reservoirs or grow chambers. Again, this material will begin to decompose, providing another food source for the pathogens.7.Clean, sterilize, and disinfect all tools and equipment used during the growing cycle, including TDS and PH testers, and gardening tools (trowels, hoses, etc), hoods, blowers, workbench, etc. Remember to dispose of properly any contaminated cleaning supplies (towels, rags, etc.)8.Keep all tanks, reservoirs, and grow chambers properly covered. This not only prevents light from getting in (crucial to keeping algae growth at a minimum) but also prevents any unwanted matter from falling into the system.9.Do not bring outdoor plants into your indoor growing environment. Outdoor plants are exposed to many more pathogens than indoor plants are, and bringing them in poses a serious contamination risk.10.After handling potentially infected material, be sure to wash your hands and any other part of your body that may have come in contact with the material. When dealing with potential pathogens or pests I prefer to wear disposable gloves so that when I’m done, I pitch the gloves and avoid getting any contaminants on me.

So you followed nearly everything on that list and you still got root rot, now what?

Treatment methods will vary depending on the severity of the infection, but there are some methods that are generally considered acceptable. First and foremost, if you decide to use chemicals to treat root rot, make sure they do not leave behind any residues. Some chemicals can leave behind residues that will not break down easily, and can cause serious problems with plants.

Most preventative measures will include the use of an enzyme product (such as Hygrozyme) to facilitate the breakdown of dead matter. Hygrozyme, used at 10mL-15mL per gallon will ensure that any dead organic matter that finds its way into the growing systems will be consumed and converted into a usable mineral matrix for your plants. Hygrozyme works great for this purpose and has the added benefit of being a bacteria free enzyme concentrate. When trying to remove a pathogen I don’t see much point in adding new bacteria into the system. (Yes, some enzyme concentrates DO contain bacteria in addition to the enzymes.) Hygrozyme is also great to use to clean your equipment mid-cycle. It has no toxic ingredients, leaves behind no residues, is OMRI certified and is completely safe for any types of plants whether in soil or hydroponics.

There are fungicides available commercially that will work to suppress and control Pythium, look for products containing the Trichoderma genus of fungi. There is some evidence that the Bacillus subtilis can also play a role in preventing and controlling certain root zone problems. (Hydroguard is a commercially available biological water treatment containing B. subtilis.) Again, these fungicides are at their best when used in an overall preventative capacity.

The fact of the matter is that Pythium can be a real bear to get rid of, especially if we desire to save the plants that are infected. Any failure to rid the system completely of Pythium will just result in the new roots that our plants grow to succumb to the same infection that got the previous ones. Only through proper preventative measures including a clean grow environment, Hygrozyme or a similar product to ensure no dead matter is present in the reservoir, proper sterilization between cycles, and a careful eye can we ensure that our plants remain as healthy and as vigorous as possible

this might work it seems interesting thought i have not tried it yet, hope i dont need to, lol http://controlpythium.info/

__________________FRESH BEANS Co.(COMMING THIS SUMMER)

Quote:

“If voting made any difference they wouldn't let﻿ us do it.” - Mark Twain

Quote:

NEVER ARGUE WITH AN IDIOT, HE WILL LOWER YOU TO HIS LEVEL AND BEAT YOU BY EXPERIENCE

Browning root rot or Pythium root rot is predominantly a seedling disease, causing reduced stands, delayed maturity and yield reductions. Pythium is most frequent where soil oxygen levels are low due to high rainfall. In western Canada, disease develops in wet soils low in phosphorus and organic matter. Spores of Pythium survive for many years in soil and crop residue. Worst outbreaks with heaviest damage occur when a dry spell is followed by abundant rain.
Scouting

Damping off occurs frequently when germination takes place under wet conditions. Seedlings that emerge usually recover but may experience impaired root development and delayed maturity. Look for disease symptoms in patches throughout fields, especially waterlogged areas. Infected plants become chlorotic and lower leaves turn yellow, then brown. Underground, look for dead root tips on small plants and brown lesions on roots of larger plants, particularly at tips of young roots.

Pythium aphanidermatum is a cosmopolitan pathogen with a wide host range. It is an aggressive species of Pythium, causing damping off, root and stem rots, and blights of grasses and fruit. It is of economic concern on most annuals, cucurbits, and grasses. It is considered one of the water molds because it survives and grows best in wet soils. Warm temperatures favor the pathogen, making it an issue in most greenhouses.

Identification

Oospore with sporangiaPythium is an Oomycete in the order Peronosprales. The hyphae are hyaline and the mycelium has no cross walls. To differentiate P. aphanidermatum from other Pythium species requires examination under a microscope of the sporangia, oogonia and antheridia. Sporangia are the asexual spores and in the case of P. aphanidermatum, they are lobate (inflated). The apluerotic oogonium, (oospore doesn't fill the oogonium) and the intercallary (rarely terminal) attachment of the antheridia further distinguishes P. aphanidermatum from other Pythium species.

Isolation

P. aphanidermatum on Corn Meal Agar and V8 Agar (Courtesy of Gloria Abad)Best results for isolation of P. aphanidermatum from plant tissue is by rinsing the tissue in tap water, rinsing in sterile water, blotting dry on sterile paper towels and then plating on a selective medium. Some of the most commonly used media are P5ARP and Pythium aphanidermatum medium. The antibiotics in these media limit bacterial contamination and pimaricin will prevent growth of Phytophthora species.

When isolating from soil, soil dilution plating is the most efficient method. Air-dried soil samples are added to 10-ml water blanks, vortexed and a small volume is pipetted onto selective medium plates. A sterile, bent glass rod is used to disperse the sample over the entire plate. The plates should be stored upside down and read in 24 hours.
Host Range and Distribution

Pythium aphanidermatum occurs world wide, particularly in warm regions and greenhouses. The fungus prefers temperatures between 27 and 34 C and wet conditions (water potential of 0 to –0.01 bars). It has a very wide host range, including many annuals and bedding plants. It causes economic losses on beets, pepper, chrysanthemum, cucurbits, cotton, and grasses.
Pathogen Life Cycle

Pythium survives in the soil as oospores, hyphae and sporangia. The fungus can survive unfavorable soil moisture and temperatures for several years as oospores. Oospores may form a germ tube directly to infect the plant or they may form sporangia. The sporangia produce zoospores, which are the motile form of the fungus. The zoospores swim around briefly before encysting and forming a germ tube, which can cause infection. Sporangia that have developed on plant tissue can germinate in a similar manner as the oospores, by either germinating directly or by forming zoospores. The pathogen is dispersed when infected debris is transported to uninfested areas and when the soil moisture is enough to allow the zoospores to swim freely.

Damping off of lettucePlants are most vulnerable to infection by P. aphanidermatum during the germination and juvenile stages. The initial symptoms may be poor or uneven germination (pre-emergence damping off). Seedlings that do germinate are susceptible to post-emergence damping-off. An infected seedling will appear water-soaked and the plant will collapse. Entire plantings can be completely destroyed at this stage.

Stem Rot

Stem rot infects the lower stem of many annual and bedding plants, especially during the juvenile stage. Symptoms begin as a water soaked region near the soil line. The plant tissue becomes slimy. If the lesion expands to encircle the stem, the plant will collapse. If the pathogen is limited by the plant, the lesion will eventually dry out and the plant begins to recover. The lesion eventually becomes sunken and is brown in color.

Root and Stem Rot

Root Rot

Pythium root rot causes wilting, loss of vigor, stunting, chlorosis and leaf drop. Root growth is inhibited and roots are blackened, mushy and rotten. Symptoms begin at the root tips. The rotten part of the roots may slough off exposing the inner root core. Underground storage structures are also at risk of infection by P. aphanidermatum. Even mature tissue can be infected and destroyed. Beets and other fleshy plant organs are susceptible to rot in the field and during storage.

Pythium Blight of Turf grasses
Pythium Blight on Rye GrassPythium blight is an aggressive disease of turf grasses. The grasses usually die and are slow to recover. The blight begins as small (six inch), circular, reddish brown spots that begin to coalesce. The grass leaves take on a dark green, water-soaked appearance and cottony mycelium may be present on the blades of grass.

Cottony Blight
Cottony Blight on CucumbersAbove ground, mature plant tissue is susceptible to infection to infection by P. aphanidermatum, particularly when it is in contact with the soil. It is most commonly seen on cucumbers and other cucurbits. The blight begins as water soaked regions, later enlarging and developing cottony mycelium on the rotting fruit.

Control Measures

Cultural Practices

Proper sanitation can greatly reduce the risk of infection by P. aphanidermatum. Use of clean pots, media and plant material can help prevent the infection of plants by the fungus. Proper air circulation between plants can make conditions less favorable for disease development. Poor drainage is a contributing factor to the dispersal of Pythium, as with other water mold fungi. A key to controlling disease development is to keep soil well drained and to avoid over irrigating. A well-drained soil not only limits the dispersal of zoospores, but also prevents plants from becoming predisposed to root rot fungi. Growing the plants at optimum conditions will limit the disease, since vigorous plants are less likely to be infected and more likely to recover.

Fungicides

Soil drenches of many fungicides are effective in controlling P. aphanidermatum. Subdue Maxx, Fore and Alliette are registered for use on lawns. Several fungicides are available for control of P. aphanidermatum on nursery crops. The appropriate treatment depends on the specific plant. Subdue is registered for use on begonia, chrysanthemum Iris and pansy. Ridomil Gold is registered for use on beans, beets, broccoli and cucumbers. For all crops, lower rates can be used for preventative control and higher rates for curative control.

__________________FRESH BEANS Co.(COMMING THIS SUMMER)

Quote:

“If voting made any difference they wouldn't let﻿ us do it.” - Mark Twain

Quote:

NEVER ARGUE WITH AN IDIOT, HE WILL LOWER YOU TO HIS LEVEL AND BEAT YOU BY EXPERIENCE

Introduction
"Root rot" is a common waterborne disease that can seriously affect indoor and outdoor crops year round. "Pythium" is a generic term for several different root rot and stem rot fungus species (including Pythium, Verticillium, and Phytophthora, and Fusarium). Root rot is also known as "damping-off" in seeds, seedlings and clones.

Pythium can rapidly infect crops in vegetative and flowering stages. Damage includes strain infection, reduced yields, and crop failure. Pythium is particularly damaging in high-density dwc / hydroponic / aeroponic systems, as these recirculating systems provide ideal conditions for rapid growth and spread of pythium spores. One infected plant can quickly spread rot to all plants if the system has an interconected irrigation system.

Dissolved oxygen, temperature and pythium
The amount of dissolved oxygen (DO) in a nutrient solution depends on the water temperature. Cold water can 'hold' more dissolved oxygen. A fully aerated solution at 20C/68 F is 9 - 10ppm; at 30C/86F it's 7ppm.

Root oxygen requirement doubles for each 10C rise in root system temperature (max 30C/86F). The dilemma for the grower is that with a 10C rise in temperature, root system oxygen requirements will double, while the oxygen carrying capacity of the solution will drop by over 25%!

The nutrient DO is unable to supply the root's oxygen demands, leading to prolonged oxygen starvation. Oxygen starvation will result in slow growth, mineral deficiencies, root die-back and reduced yields. Oxygen starvation will stress the plant, leading to an eventual attack by opportunistic pathogens, such as ever-present pythium.

Advanced:
# Brown and slimy roots with a slight to strong rotting odor. Plant may appear healthy.
# Reddish and swollen root collar, becoming blackened over time. Eventually the plant will fall over as all connecting tissue will have been 'eaten away'.

Note: Root damage is permanent; new root hairs can form, but damaged roots will not regenerate. Lightly infected roots may turn white again if treated promptly.

Management Strategies
Keeping the crop healthy, vigorous and stress-free is the best "cure" against pythium. Pythium is almost impossible to 100% eradicate from an infected system; this involves starting completely over (with new mothers, containers, equipment, etc). An infected crop can be nursed along, and subsequent crops can still yield, provided the grower takes care to minimize the growth and spread of pythium in the system.

Starting with a pythium-free system is the best strategy:

Startup with a new crop:
-disinfect the system. Manual scrubbing and bleach might be necessary.
-add tap water
-disinfect the water with strong h2o2. It takes 100ppm to kill pythium outright, however this can also kill small plants. Wait 24 hours for h2o2 to dissipate to a safe level - do not add tap water to system! Add only h2o2-treated water.
-add nutrients and beneficial enzymes. The aerobic-loving enzymes will colonize the sterilized medium and system, hopefully displacing any anaerobic bacteria.

Soil tips:
Improved soil is the first step to keeping root rot out of your garden. Adding amendments to improve drainage and aeration will decrease the chances of root rot. Use only sterilized soil/soilless mixes or heat-treated soil before use.
Removing the diseased plants and several inches of affected soil will slow or stop the spread of pythium. Avoid over watering, as saturated soil promotes anaerobic conditions. Remove and destroy roots and surrounding soil near infected plants. Use sterilized soil for transplants. Provide good drainage and avoid overcrowding plants.

Special tips for bubblers:
(highgrade) "Have an empty, sterile bucket to place the bubbling bucket into when changing nutes. The extra bucket method allows me to run a gallon of water through the pot and flush the grorocs and root mass of any salt build up. Wash the bucket prior to refilling with solution."

(Baudelaire) "… maintain a humid air gap extending from the root crown down at least 4 inches. This provides the space for aerial roots to form, and keeps water away from the root collar, where root rot typically takes hold."

Emergency Treatment: top

1. Hydrogen Peroxide root dunk
-Remove each plant from system, snip off potions of the roots system badly diseased.
-Dip/swish each plant and container into a strong H2O2 solution, until diseased roots have been removed. Repeat as required. The H2O2 should burn off the pythium-infected outer root layers.

2. Sterilize equipment
All equipment should be disinfected (including hoses and pots, etc) with bleach solution or 10% h2o2 solution before plants are reintroduced into the system. Rinse well.

Experimental
# UV Sterilizers. UV can kill waterborne organisms, with a slow exposure to UV light. Research suggests iron can precipitate out of solution. Pythium already attached to surfaces in the rootzone will not flow through the sterilizer and not be killed. Aquarium stores sell them.

# Continuous drip H2o2. According to Maximum Yield, 100ppm is required to kill pythium in solution. This level also adversely affects small plants. Of course, organics and beneficial bacteria in additives will also be destroyed.

H2o2 should be added to a seperate volume of water and allowed to sit for 20 minutes before adding to the reservoir. The majority of the O2 will be chemically released by the H2o2 by that point. (In high enough concentration, h2o2 will burn off the epeidermis of the roots, exposing it to attack by pathogens and damging fine root hairs).

# Slow sand filtration. According to interet literature, SSF can remove up to 99.7% of all bacteria. Aquarium stores sell sand filters.

# Dissolved Oxygen machines. Artifically injecting water with oxygen may inhibit or kill pytium and other anerobic organisms.

__________________FRESH BEANS Co.(COMMING THIS SUMMER)

Quote:

“If voting made any difference they wouldn't let﻿ us do it.” - Mark Twain

Quote:

NEVER ARGUE WITH AN IDIOT, HE WILL LOWER YOU TO HIS LEVEL AND BEAT YOU BY EXPERIENCE

Pythium Root Rot in Soil and Hydroponic Applications
There is no doubt that Pythium is much more devastating in a hydroponic application when compared to a soil application. This is due in large part to the fact that Pythium has adapted very well to live in water. Certain varieties of Pythium will produce what are known as zoospores (small, flagellated spores) that are extremely small, motile spores able to move in water. These spores are able to move from plant to plant via the water in the system, colonizing and infecting along the way. They even have the ability to remain viable for long periods of time in soil and in the nooks and crannies of a hydroponic system.
That is not to say that soil/container gardeners should leave Pythium untreated. Regardless of media, the pathogen will eventually find its way to the root system and begin to wreak havoc. But soil gardeners get a distinct advantage in the fight vs. Pythium. The root system of the plant (along with any mycorrhizal networks present) creates a web-like barrier that can slow down the spread the Pythium. The symbiotic relationship between the mycorrhizal fungi and the roots of the plant not only provide enhanced access to carbohydrates, water, and minerals, but also provide additional benefits such as increased resistance to diseases and drought.

Blumat adjustment procedure: (for soil)In a bucket ,fill and soak units under water for at LEAST an hour. Then screw on cap( nice and tight!) under water making sure not to trap any air.Leave dripper line at ~8cm. long.
Give the pot a good watering.
Insert B/M snugly into nicely compacted soil(not too loose) .
Open till water comes out, carefully close until just a drop barely forms.
Tighten 1.75 - 2 Arrows
Adjust as necessary for a few days, then leave it alone!

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